Steam boiler system



F. J. SMITH STEAM BOILER SYSTEM Filed 0G12. l5, 1965 Dec. 27, 1966'United States Patent O 3,294,069 STEAM BOILER SYSTEM Frank J. Smith,7351 Limeklin Pike, Philadelphia, Pa. 19138 Filed Oct. 15, 1965, Ser.No. 496,262 4 Claims. (Cl. 1221) This invention relates to a steamboiler system, particularly to an improved sys-tem of high pressure andlow pressure steam boilers and related equipment, of the type havingsubstantial make-up water demands, arranged in a unique operationalcombination, and has for an object the provision of improvements in thisart.

With the exception of low pressure steam heating systems in which thecondensate is returned to the boilers with little or no loss andtherefore little or no makeup, the problem of scale deposits andcorrosion of the internal surfaces of the metal comprising the shellplates, heads, drums, and tubes of the boilers is of universal concern.

The problem becomes more acute as steam pressures and relatedtemperatures are increased. Since scale is an insulation that retardstransfer of heat from the hot metal of the boiler surfaces to the water,increasing thicknesses of scale result in increased metal temperaturesand ultimate failure of the metal.

All makeup boiler feedwaters, whether from municipal systems or fromwells, lakes or streams, contain in varying amounts corrosive gases andharmful dissolved salts. Treating systems range from simple methods ofintroducing chemicals directly into the boiler itself to elaborate andexpensive external systems incorporating the use of deaerating equipmentto remove as much of the corrosive gases as possible, the use of ionexchange systems of either, or a combination of, sodium and acid cyclesthat are capable of producing water of almost any degree of chemicalpurity.

Boiler feedwater purification by means of distillation is practiced onlyin systems involving extremely large high pressure and high temperatureboilers such as in public utility plants, where pure water is vitallyneeded to avoid burned out tubes and turbine blade deposits caused whensmall amounts of impurities are carried into the boilers with thefeedwater.

There are many installations, as in laundries, dairies, dye houses, foodprocessing plants, and the like, where the sys-tem disclosed herein canbe advantageously used to provide distilled and deaerated feedwater tothe high pressure boiler or boilers and furnish an excess amount of thisrelatively pure water for special processes and for sale on the market.

Accordingly, it is a particular object of the present invention toprovide a system in which a high pressure boiler system is supplied withdeaerated condensate from its own system plus needed makeup deaeratedcondensate supplied from a low pressure boiler system, which system, inturn, has been supplied with deaerated water from a softening system.

Another object of the invention is to permit the use of steam generatingequipment for operation at substantially increased pressures andtemperatures than is now cornmonly used, thereby increasing the economicefficiencies of the plants by permitting the use of more etlicienftpumps, fans, blowers, and turbo electric generators not possible whenoperating at lower pressures and temperatures.

Another object is to provide a system which supplies highly purifieddeaerated distilled water as an economical by-product for use whereverneeded.

The above and other objects of the invention, as well as various novelfeatures and advantages, will be apparent from the following descriptionof an exemplary embodi- "ice ment, reference being made to theaccompanying drawings thereof, wherein:

The single figure is an elevational diagram of an installation orsys-tem embodying the invention.

In the drawings there is shown a low pressure steam boiler 10, a highpressure steam boiler 11, a water softener unit 12, a heat exchangewater heater 13, a steam load demand 14 of the high pressure boiler, afeed water deaerating heater unit 15 for the low pressure boiler, acondensate deaerating heater unit 16 for the high pressure boiler, astorage tank 17 for the deaerating heater unit 16, and a reservoir 18for highly purified water.

A pipe line 20 supplies raw water to the sof-tener 12; a pipe line 21supplies soft water from the softener to the exchange water heater 13; apipe line 22 carries hot offtake water from the heater 13; a firstbranch pipe line 23 carries water from the pipe 22 and heater 13 to theprocess demand means 24; and a second branch pipe line 25 carries waterfrom the pipe line 22 and heater 13 to supply the low pressure boiler10.

Water from the pipe line 25 is not fed directly into the low pressureboiler 10 but is first passed by a pipe line 26 into the top of the feedwater deaerating heater 15 where steam from a branch line 27 of the lowpressure boiler 10 is supplied for the de-aerating action of thecondensate deaerating heater 15. Steam to deaerating heater 16 issupplied by a branch pipe line 59 from the low pressure boiler 10. Apipe line 28 takes deaerated water from the unit 15 to the header drum29 of the boiler 10. A valve 30, responsive to the level of water in theheader 29, controls the iiow of water to the pipe line 26 and lthedeaerating heater 15.

Steam from the header drum 29 Iof the low pressure boiler 10 flows byway of a pipe line 33 to a heating coil 34 in the water heater 13 andreturns as condensate by a pipe line 35 to the condensate deaeratingheater 16, a steam trap 36 being provided in the condensate return line35. The flow of steam to the heating coil 34 is regulated by athermostat valve 37 controlled by a thermostat 38 in 4the heater tankacting through a connecting cable line 39. The control connection may beother than electrical but this is shown for illustrative purposes.

Steam from the header drum 40 of the high pressure boiler 11 flows tothe steam demand process equipment 14 by way of the pipe line 43 andIthe condensate flows out by way of a pipe line 44 to the deaeratingheater 16, a steam trap 45 being disposed in the line 44 to permit onlythe condensate to flow.

Highly purified condensate liquid from the storage -tank 17 of thedeaerating heater 16 is taken off through a pipe -line 46 by a pump P1driven by a motor M1 and delivered by a pipe line 47 to the header drum40 of the high pressure boiler 11, a liquid level-controlled valve 48,through an electrical cable line 49 or the equivalent, regulating theoperation of the motor M1.

Excess highly purified liquid condensate from the tank 17 of thedeaerating heater flows by an overflow pipe line 50 to the reservoir 18.Liquid from the reservoir 18 is returned, as may be needed to maintainliquid in the tank 17, lby a pipe line 53 to a pump P2 driven by a motorM2, the pump forcing the liquid by way of a pipe line 54 to the top ofthe deaerating heater 16. A liquid level controlled valve 55, regulatedas by a float in the tank 17, controls the operation Iof the motor M2through an electrical cable line 56 or the equivalent.

If the reservoir 18 is full of water the excess is taken off by way of apipe line 57 from the top of the reservoir leading to a storage tank 58for use as highly purified deaerated water for any desired purposes.

While the general function of deaerating heaters is well known, theirparticular location and function in the present system has special andvery beneficial functions and advantages. The feed water deaeratingheater 15 serves to supply the low pressure boiler with water which hasmost of the corrosive gases removed. But some corrosive gases remain orare formed in the low pressure boiler and return in its steamcondensate. The condensate deaerating heater 16 serves the veryimportant function of removing substantially all of the residualcorrosive gases from the condensate whereby the high pressure boiler issupplied with water which is substantially or entirely free fromcorrosive and scaling effects. This is especially beneficial since it isthe high pressure boiler which is harmfully affected by such impuritiesand in which it is most difficult and expensive to eliminate the harmfuleffects of such impurities. The effects of some impurities in the lowpressure boiler are not so serious and are much more easily overcome.

It will be seen that the high pressure boiler is always supplied withhighly purified water which has: (1) passed through the softener 12; (2)been passed through the deaerating heater 15; (3) been evaporated in thelow pressure boiler 10; (4) been condensed in coil 34; and (5) beenpassed through the second deaerating heater 16.

While one embodiment of the invention has been described for purposes ofillustration, it is to be understood that there may be variousembodiments and modifications within the general scope of the invention.

I claim:

1. A steam boiler system, comprising in combination, a low pressureboiler, a high pressure boiler, means for supplying source water firstto the low pressure boiler, a condensate deaerating heater for theliquid supply to said high pressure boiler, a steam load unit suppliedwith steam from said low pressure boiler and having a steam condensatereturn, means for supplying condensate from the low pressure boiler tosaid condensate deaerating heater for the high pressure boiler, meansfor returning condensate from the high pressure boiler back into saidcondensate deaerating heater along with the condensate from the lowpressure boiler, and means for supplying steam from said low pressureboiler to said condenstate deaerating heater.

2. A steam boiler installation as set forth in claim 1, which furtherincludes in combination, a water softener for pretreating the Watersupplied to the low pressure boiler a feed water deaerating heater forsoftened water supplied to said low pressure boiler, and means forsupplying steam from said low pressure boiler to said feed waterdeaerating heater.

3. A steam boiler system as set forth in claim 1, which further includesin combination, a water level-controlled tank for supplying condensatewater from said condensate deaerating heater to said high pressureboiler, a reservoir for holding overflow condensate from said tank,means for returning water from said reservoir to said tank, and meansfor drawing off excess water from said reservoir.

4. A steam boiler system as set forth in claim 2, which further includesin combination, an exchange water heater, comprising part of said steamload unit of the low pressure boiler, for heating softened water fromsaid softener and supplying it to said feed water deaerating heater forsaid l-ow pressure boiler, a reservoir arranged to receive surplusexcess water from said condensate deaerating heater, means for returningwater from said reservoir to said condensate deaerating heater, andmeans for delivering excess water from said reservoir for use outsidesaid system.

References Cited by the Examiner UNITED STATES PATENTS KENNETH W.SPRAGUE, Primary Examiner.

1. A STEAM BOILER SYSTEM, COMPRISING IN COMBINATION, A LOW PRESSUREBOILER, A HIGH PRESSURE BOILER, MEANS FOR SUPPLING SOURCE WATER FIRST TOTHE LOW PRESSURE BOILER, A CONDENSATE DEAERATING HEATER FOR THE LIQUIDSUPPLY TO SAID HIGH PRESSURE BOILER, A STEAM LOAD UNIT SUPPLIED WITHSTEAM FROM SAID LOW PRESSURE BOILER AND HAVING A STEAM CONDENSATERETURN, MEANS FOR SUPPLYING CONDENSATE FROM THE LOW PRESSURE BOILER TOSAID CONDENSATER DEAERATING HEATER FOR THE HIGH PRESSURE BOILER, MEANSFOR RETURNING CONDENSATE FROM THE HIGH PRESSURE BOILER BACK INTO SAIDCONDENSATE DEAERATING HEATER ALONG WITH THE CONDENSATE FROM THE LOWPRESSURE BOILER, AND MEANS FOR SUPPLYING STEAM FROM SAID LOW PRESSUREBOILER TO SAID CONDENSTATE DEAERATING HEATER.